1. Field of the Invention
The present invention relates to a chemical luminescence-detecting apparatus in which an intensity of a chemical luminescence generated in a photometric cell is detected by an optical detector and, more particularly, to the use of multiple optical detectors with predetermined cooperative characteristics.
2. Description of Related Art
The measurement of the luminescence produced, for example, in a chemical reaction, has been successfully utilized. For example, an enzyme immuno assay system capable of measuring various substances found in blood, such as carcino embryonic antigen (CEA), ferritin (FER), .alpha.-fetoprotein (AFP), and thyroxine binding globulin (TBG) is known. Generally, a sample to be measured is put into a container such as a tube that may have a predetermined antibody substance in the tube in order to permit a reaction to be carried out. A substrate solution can be added to carry out an enzyme reaction, thereby generating a reaction liquid containing, for example, hydrogen peroxide. A portion of the resulting reaction liquid containing the hydrogen peroxide can then be placed into the photometric sample cell or tube, together with a luminescent reagent, to measure the substances contained within the tube by detecting the intensity of a chemical luminescence generated in the photometric cell.
Referring to FIG. 11, the schematic of a prior art chemical luminescence-detecting apparatus is disclosed. This apparatus can comprise a cylindrical photometric cell or tube 91 made of glass or plastic, which can be fixedly mounted on an integrated spherical cell holder 92. A shutter mechanism 93 can control light emitting from the photometric cell 91. Adjacent the shutter mechanism 93 is a photomultiplier tube 94 that can receive and detect the chemical luminescence being generated by the reaction within the test cell 91. This apparatus would be useful in a so-called batch-type measuring system, and a high voltage power source 95 can be connected to the photomultiplier tube 94. The output from the photomultiplier tube 94 can be appropriately amplified by an amplifier 96 prior to subsequent signal processing.
According to the conventional luminescence-detecting apparatus shown in FIG. 11, only one photomultiplier tube 94 is provided for measuring the output of the photometric cell 91. In order to enable an increased range of measurement by the photomultiplier tube 94 under similar conditions, it has been frequently necessary to carry out the measurement while regulating other parameters of the system, for example, by varying the supply voltage from the high voltage power source 95, by varying the value of any feedback resistance in the amplifier circuit and the like.
A problem has existed in that the conventional chemical luminescence apparatus can be limited in its ability to accommodate a wide range of measurements. For example, in the enzyme immune measurement systems it has been difficult to use a conventional chemical luminescence-detecting apparatus, since a large number of items must be randomly measured during the enzyme immune measurement system, so that a corresponding large range of quantities of light to be measured can occur. It becomes further difficult to modify the system so that measurements can be carried out by means of only a single optical detector. These problems exist not only in the batch-type measuring method, but also in the so-called flow through-type measuring method that can, for example, use a spiral flow through-type photometric cell.
The prior art is still seeking to optimize chemical luminescence-detecting apparatus that can accommodate the broader demands of, for example, an enzyme immune measurement system in an economical and highly efficient manner.